1. Field of the Invention
The invention in general relates to the detection of ferrous objects, and particularly, to a system for determining whether or not an object detected in the bed of a body of water is likely to be a naval mine.
2. Description of the Prior Art
Sonar systems, particularly side-looking sonar systems, are adept at detecting naval mines lying on, or moored just above the bed of a body of water. Mine detection becomes more difficult, and in some cases impossible, when the mine is buried in the bottom.
A number of magnetic systems have been developed for mine detection, one outstanding example of which is the superconducting gradiometer system. This type of system utilizes several pairs of superconducting magnetometers to measure spatial gradients of the static magnetic field produced by the mine. Such systems must carry cryogenic cooling equipment containing liquid helium for proper magnetometer operation and very sophisticated computing equipment is required for the complex signal processing performed.
Very often a detected mine is neutralized by depositing and detonating an explosive charge over its detected location. Although the superconducting gradiometer system is excellent for detecting the mine, it is a far too costly system to risk for delivering an explosive charge for mine neutralization.
The present invention is a relatively inexpensive scalar gradiometer system which can reacquire a previously detected mine, can add independent verification as to whether the detected object is a mine, and can be utilized in the mine neutralization process. In case of an accident which would damage or destroy the system, the system could be repaired or replaced at a much lower cost than the superconducting gradiometer arrangement. Further, the present invention does not require complex cryogenic cooling equipment for operation, and makes use of relatively simple signal processing equipment and algorithms.